The invention relates to a cartridge munition, particularly to one of medium caliber, and here particularly to a practice round, with a cartridge shell and a projectile inserted into it, and with the cartridge shell mechanically attached to the projectile. A propulsion chamber is provided at the base of the cartridge shell to receive a propulsive charge that, for example, may be ignited using an igniter cap. After ignition, the propulsive gases from the propulsive charge act on the base of the projectile so that, after release of the mechanical bond between cartridge shell and projectile, the projectile is driven out of the cartridge shell.
Such a cartridge munition is described in the U.S. Pat. No. 5,936,189. This cartridge munition is used with rapid-fire weapons of medium caliber (about 40 mm). Many such cartridges are received into a belt that is fed to the rapid-fire weapon. The propulsion chamber in the cartridge shell is sub-divided into a high-pressure chamber into which the propulsive charge is placed and a low-pressure chamber that is connected with the high-pressure chamber via exhaust apertures. Cartridge shell and projectile are mechanically connected via a central threaded connection that is formed as an intended-break point.
When the propulsive charge is ignited pyrotechnically in the high-pressure chamber by means of an igniter cap, the propulsive charge burns and propulsive gases are created at high pressure that then act on the projectile base in both chambers, eventually driving the projectile out of the cartridge shell, after the intended-break point between cartridge shell and projectile is broken.
A similar cartridge munition is described in the U.S. Pat. No. 4,892,038.
Furthermore, practice rounds of this type are known in which only a low-pressure propulsion chamber is provided; such cartridges are known as low-velocity cartridges (Low Velocity Ammunition).
Such cartridge munitions are used in large quantities, and must both be safely stored and safely transported from the manufacturer to the user. Storage and transport are generally performed using larger cases, e.g., metal cases that hold a large quantity of such cartridges.
In spite of the considerable quantity of igniter material for igniter caps and propulsive charge located within a storage or transport container, storage and transport are generally simple. However, a fire in the storage or transport system during which temperatures reach and exceed 220° C. presents a risk.
At such temperatures, the pyrotechnic igniter charge of the igniter cap combusts spontaneously, igniting in turn the propulsive charge that otherwise would have ignited at a temperature from 320° C. to 400° C. After the propulsive charge ignites, as during regular firing, enough pressure develops in the propulsion chamber to act on the base of the projectile eventually to rupture the mechanical connection between cartridge shell and projectile, causing them to fly apart explosively.
Significant damage may result simply from the quantity of exploded propulsive charges of a large number of cartridges. However, the cartridge shell and projectile may cause great damage while flying apart. Cartridge shell and projectile here act quasi as projectiles. Any receiver containers involved will be destroyed, whereby the separated cartridge shells and projectiles may endanger humans and cause major mechanical damage.
During testing, such cartridges are placed into a heater, and heat is gradually supplied to the heater. After the igniter-cap ignition temperature of about 220° C. is reached, as illustrated, the igniter cap and thereby the propulsive charge of the cartridges are ignited. The cartridge shell and projectile were blown apart and thrown up to 100 meters as a result of the pressure buildup in the propulsion chamber, so that the energy released when many such cartridges catch fire is considerable.